Heater Core: Description and Operation

The heater core is located in the distribution housing of the heater-A/C unit, under the instrument panel. It is a heat exchanger made of rows of tubes and fins. One end of the core is fitted with a molded plastic tank that includes integral heater core inlet and outlet ports. The removable heater core tubes are held in place these ports by a sealing plate secured with a screw to the heater core tank. This removable heater core tube arrangement allows the heater core to be serviced without removing the heater-A/C unit housing from the vehicle. The heater core cannot be repaired and, if faulty or damaged, it must be replaced.

Engine coolant is circulated through heater hoses to the heater core at all times. As the coolant flows through the heater core, heat removed from the engine is transferred to the heater core fins and tubes. Air directed through the heater core picks up the heat from the heater core fins. The blend air door allows control of the heater output air temperature by controlling how much of the air flowing through the heater-A/C unit housing is directed through the heater core.